  <!-- 左侧导航栏 - 占1/4宽度 -->
  <div class="col-3 bg-white border-right py-4">
    <h4 class="text-center mb-4">领导信箱</h4>
    <ul class="nav flex-column">
        <li class="nav-item mb-2">
            <a class="nav-link text-dark" href="${base}/letter">
                来信选登
            </a>
        </li>
        <li class="nav-item mb-2">
            <a class="nav-link text-dark" href="${base}/letter/post">
                我要写信
            </a>
        </li>
        <li class="nav-item mb-2">
            <a class="nav-link text-dark" href="${base}/letter/query">
                查询回信
            </a>
        </li>
    </ul>
</div>